12/15-lipoxygenase is an interleukin-13 and interferon-γ counterregulated-mediator of allergic airway inflammation

A review on the relationship between Arachidonic acid 15-Lipoxygenase (ALOX15) and diabetes mellitus

Arachidonic acid 15-lipoxygenase (ALOX15), as one of the lipoxygenase family, is mainly responsible for catalyzing the oxidation of various fatty acids to produce a variety of lipid components, contributing to the pathophysiological processes of various immune and inflammatory diseases. Studies have shown that ALOX15 and its related products are widely distributed in human tissues and related to multiple diseases such as liver, cardiovascular, cerebrovascular diseases, diabetes mellitus and other diseases. Diabetes mellitus (DM), the disease studied in this article, is a metabolic disease characterized by a chronic increase in blood glucose levels, which is significantly related to inflammation, oxidative stress, ferroptosis and other mechanisms, and it has a high incidence in the population, accompanied by a variety of complications. Figuring out how ALOX15 is involved in DM is critical to understanding its role in diseases. Therefore, ALOX15 inhibitors or combination therapy containing inhibitors may deliver a novel research direction for the treatment of DM and its complications. This article aims to review the biological effect and the possible function of ALOX15 in the pathogenesis of DM.

Cordyceps militaris polysaccharide alleviates ovalbumin-induced allergic asthma through the Nrf2/HO-1 and NF-κB signaling pathways and regulates the gut microbiota

Polysaccharides, as one of the main types of bioactive components of Cordyceps militaris, have anti-allergic asthma effects. Herein, an ovalbumin-induced allergic asthma mouse model was established to assess the potential mechanisms of the separated and purified Cordyceps militaris polysaccharide (CMP). CMP is an α-pyranose with a molecular weight of 15.94 kDa that consists of Glc, Man, Gal, Xyl, Ara and GlcA in a molar ratio of 81.25:21.96:13.88:3.92:3.58:1.00. CMP improved inflammatory cytokine levels, alleviated the histopathological changes in the lung and intestinal tissues, regulated the expression of mRNA and proteins related to oxidative stress and inflammatory pathways, reversed gut dysbiosis at the phylum and family levels and improved microbiota function in allergic asthma mice. Moreover, it was found that the levels of inflammatory cytokines in lung tissue of mice were significantly correlated with some intestinal microbial communities. Overall, CMP improved oxidative stress and the inflammatory response in allergic asthma mice by regulating the Nrf2/HO-1 and NF-κB signaling pathways, which may be closely correlation with maintaining the stability of the gut microbiota.

Comparison of Overall Immunity Levels among Workers at Grape Orchard, Rose Greenhouse, and Open-Field Onion Farm

Background

Methods

Results

Conclusion

Type-2 airway inflammation in mild asthma patients with high blood eosinophils and high fractional exhaled nitric oxide

Type‐2 (T2) inflammation is a characteristic feature of asthma. Biological therapies have been developed to target T2‐inflammation in asthma. IL‐13 is a key component of T2‐inflammation in asthma, driving mucus hypersecretion, IgE‐induction, and smooth muscle contraction. Early phase clinical trials for treatments that target T2‐inflammation require biomarkers to assess pharmacological effects. The aim of this study was to examine levels of IL‐13 inducible biomarkers in the airway epithelium of patients with mild asthma compared to healthy controls. Ten patients with mild asthma with high blood eosinophil and high fractional exhaled nitric oxide (FeNO) were recruited, and six healthy subjects. Blood eosinophil and FeNO reproducibility was assessed prior to bronchoscopy. Epithelial brushings were collected and assessed for IL‐13 inducible gene expression. Blood eosinophil and FeNO levels remained consistent in both patients with asthma and healthy subjects. Of the 11 genes assessed, expression levels of 15LOX1, POSTN, CLCA1, SERPINB2, CCL26, and NOS2 were significantly higher in patients with asthma compared to healthy controls. These six genes, present in patients with mild asthma with T2 inflammation, have the potential to be used in translational early phase asthma clinical trials of novel therapies as bronchial epithelial biomarkers.

Regulation of Tissue Inflammation by 12-Lipoxygenases

Lipoxygenases (LOXs) are lipid metabolizing enzymes that catalyze the di-oxygenation of polyunsaturated fatty acids to generate active eicosanoid products. 12-lipoxygenases (12-LOXs) primarily oxygenate the 12th carbon of its substrates. Many studies have demonstrated that 12-LOXs and their eicosanoid metabolite 12-hydroxyeicosatetraenoate (12-HETE), have significant pathological implications in inflammatory diseases. Increased level of 12-LOX activity promotes stress (both oxidative and endoplasmic reticulum)-mediated inflammation, leading to damage in these tissues. 12-LOXs are also associated with enhanced cellular migration of immune cells-a characteristic of several metabolic and autoimmune disorders. Genetic depletion or pharmacological inhibition of the enzyme in animal models of various diseases has shown to be protective against disease development and/or progression in animal models in the setting of diabetes, pulmonary, cardiovascular, and metabolic disease, suggesting a translational potential of targeting the enzyme for the treatment of several disorders. In this article, we review the role of 12-LOXs in the pathogenesis of several diseases in which chronic inflammation plays an underlying role.

Predictive significance of arachidonate 15-lipoxygenase for eosinophilic chronic rhinosinusitis with nasal polyps

Background

Eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) exhibits a poorer outcome compared with non-eosinophilic chronic rhinosinusitis with nasal polyps (nonECRSwNP), so it is significant to identify effective markers to differentiate ECRSwNP in guiding the treatment strategies of these patients. Although arachidonate 15-lipoxygenase (ALOX15) is positioned as a marker of eosinophilic inflammation, its study in differentiating ECRSwNP has not been reported. The aim of this study is to assess the potential of ALOX15 in distinguishing and predicting ECRSwNP.

Methods

Forty-eight patients with chronic rhinosinusitis with nasal polyps (CRSwNP), including 30 ECRSwNP and 18 nonECRSwNP patients, were enrolled. ALOX15 mRNA level was determined in polyps by real-time polymerase chain reaction (RT-PCR). The patients’ baseline characteristics were evaluated and analyzed for correlations with ALOX15. Receiver operating characteristic (ROC) curve was used to assess the predictive significance of the potential predictors for ECRSwNP.

Results

ALOX15 mRNA level was significantly higher in ECRSwNP patients than in nonECRSwNP patients (P < 0.001). ALOX15 mRNA was significantly correlated with tissue and blood eosinophil percentages (r = 0.565, P < 0.001 and r = 0.395, P = 0.006), olfaction scores (r = 0.400, P = 0.005), total visual analogue scale (VAS) symptom scores (r = 0.383, P = 0.007), ethmoid/maxillary sinus (E/M) ratio (r = 0.463, P = 0.001), and endoscopy scores (r = 0.409, P = 0.004). Logistic regression analysis showed ALOX15 mRNA level and percentage of blood eosinophils to be predictive factors for ECRSwNP (P = 0.004 and P = 0.036, respectively). ROC curve indicated ALOX15 to have high predictive accuracy for ECRSwNP (area under the curve (AUC) = 0.909), which was further improved by combination of ALOX15 with percentage of blood eosinophils (AUC = 0.933).

Conclusions

The relative ALOX15 mRNA level alone or in combination with blood eosinophils might be a reliable biomarker for predicting a diagnosis of ECRSwNP.

Up-regulation of 15-lipoxygenase enzymes and products in functional and non-functional pituitary adenomas

Background

Pituitary adenoma accounts as a complex and multifactorial intracranial neoplasm with wide range of clinical symptoms which its underlying molecular mechanism has yet to be determined. The bioactive lipid mediators received attentions toward their contribution in cancer cell proliferation, progression and death. Amongst, 15-Lipoxygense (15-Lox) enzymes and products display appealing role in cancer pathogenesis which their possible effect in pituitary adenoma tumor genesis is perused in the current study.

Methods

The 15-Lipoxygenses isoforms expression level was evaluated in tumor tissues of prevalent functional and non-functional pituitary adenomas and normal pituitary tissues via Real-Time PCR. The circulating levels of 15(S) HETE and 13(S) HODE as 15-Lox main products were assessed in serum of patients and healthy subjects using enzyme immunoassay kits.

Results

Our results revealed that 15-Lox-1 and 15-Lox-2 expression levels were elevated in tumor tissues of pituitary adenomas comparing to normal pituitary tissues. The elevated levels of both isoforms were accompanied with 15(S) HETE and 13(S) HODE elevation in the serum of patients. The 15-Lox-1 expression and activity was higher in invasive tumors as well as tumors with bigger size indicating the possible pro-tumorigenic role of 15-Lox-1, more than 15-Lox-2 in pituitary adenomas. The diagnostic value of 15-Lipoxygense isoforms and products were considerable between patients and healthy groups.

Conclusion

The possible involvement of 15-Lipoxygense pathway especially 15-Lox-1 in the regulation of pituitary tumor growth and progression may open up new molecular mechanism regarding pituitary adenoma pathogenesis and might shed light on its new therapeutic strategies.

Altered immune responses in broiler chicken husbandry workers and their association with endotoxin exposure

Exposure to bioaerosols in indoor animal farms associates with respiratory illnesses, but little is known about the immune modulation to chicken farmers. This study aimed to compare the general immunity of chicken farmers with those of control subjects with non-agricultural jobs. Blood taken from the farmers and controls was subjected to plasma IgE and IgG subclass measurements. Isolated peripheral blood mononuclear cells (PBMC) were stimulated and cytokine production was measured. Indoor total and respirable dust levels and their endotoxin (LPS) and aflatoxin (AF) levels in the farms were measured. In total, 29 chicken farmers on 19 farms and 14 age- and sex-matched office workers participated. Hematological differences were not observed. The farmers tended to have higher serum IgE and IgG subclass levels with significance for IgG1. The cytokines released by PBMC from farmers indicated skewing toward Type-2 helper T-cell responses: interferon (IFN)-γ:interleukin (IL)-4 and IFNγ:IL-13 ratios were significantly lower than for control PBMC. The farms had 707.1 EU/m3 LPS in total dust, and 15.8 EU/m3 LPS in respirable dust. Farmers exhibited immune skewing towards allergic immune responses that correlated with the LPS levels on their farms. Chicken farmers may be at risk of respiratory allergies due to occupational endotoxin exposure.

The nasal methylome and childhood atopic asthma

BACKGROUND

Given the strong environmental influence on both epigenetic marks and allergic asthma in children, the epigenetic alterations in respiratory epithelia might provide insight into allergic asthma.

OBJECTIVE

We sought to identify DNA methylation and gene expression changes associated with childhood allergic persistent asthma.

METHODS

We compared genomic DNA methylation patterns and gene expression in African American children with persistent atopic asthma (n = 36) versus healthy control subjects (n = 36). Results were validated in an independent population of asthmatic children (n = 30) by using a shared healthy control population (n = 36) and in an independent population of white adult atopic asthmatic patients (n = 12) and control subjects (n = 12).

RESULTS

We identified 186 genes with significant methylation changes, differentially methylated regions or differentially methylated probes, after adjustment for age, sex, race/ethnicity, batch effects, inflation, and multiple comparisons. Genes differentially methylated included those with established roles in asthma and atopy and genes related to extracellular matrix, immunity, cell adhesion, epigenetic regulation, and airflow obstruction. The methylation changes were substantial (median, 9.5%; range, 2.6% to 29.5%). Hypomethylated and hypermethylated genes were associated with increased and decreased gene expression, respectively (P < 2.8 × 10^-6 for differentially methylated regions and P < 7.8 × 10^-10 for differentially methylated probes). Quantitative analysis in 53 differentially expressed genes demonstrated that 32 (60%) have significant methylation-expression relationships within 5 kb of the gene. Ten loci selected based on the relevance to asthma, magnitude of methylation change, and methylation-expression relationships were validated in an independent cohort of children with atopic asthma. Sixty-seven of 186 genes also have significant asthma-associated methylation changes in nasal epithelia of adult white asthmatic patients.

CONCLUSIONS

Epigenetic marks in respiratory epithelia are associated with allergic asthma and gene expression changes in inner-city children.

Activity-Based Probes for 15-Lipoxygenase-1

Human 15-lipoxygenase-1 (15-LOX-1) plays an important role in several inflammatory lung diseases, such as asthma, COPD, and chronic bronchitis, as well as various CNS diseases, such as Alzheimer's disease, Parkinson's disease, and stroke. Activity-based probes of 15-LOX-1 are required to explore the role of this enzyme further and to enable drug discovery. In this study, we developed a 15-LOX-1 activity-based probe for the efficient activity-based labeling of recombinant 15-LOX-1. 15-LOX-1-dependent labeling in cell lysates and tissue samples was also possible. To mimic the natural substrate of the enzyme, we designed activity-based probes that covalently bind to the active enzyme and include a terminal alkene as a chemical reporter for the bioorthogonal linkage of a detectable functionality through an oxidative Heck reaction. The activity-based labeling of 15-LOX-1 should enable the investigation and identification of this enzyme in complex biological samples, thus opening up completely new opportunities for drug discovery.

Design of a novel thiophene inhibitor of 15-lipoxygenase-1 with both anti-inflammatory and neuroprotective properties

The enzyme 15-lipoxygenase-1 (15-LOX-1) plays a dual role in diseases with an inflammatory component. On one hand 15-LOX-1 plays a role in pro-inflammatory gene expression and on the other hand it has been shown to be involved in central nervous system (CNS) disorders by its ability to mediate oxidative stress and damage of mitochondrial membranes under hypoxic conditions. In order to further explore applications in the CNS, novel 15-LOX-1 inhibitors with favorable physicochemical properties need to be developed. Here, we present Substitution Oriented Screening (SOS) in combination with Multi Component Chemistry (MCR) as an effective strategy to identify a diversely substituted small heterocyclic inhibitors for 15-LOX-1, denoted ThioLox, with physicochemical properties superior to previously identified inhibitors. Ex vivo biological evaluation in precision-cut lung slices (PCLS) showed inhibition of pro-inflammatory gene expression and in vitro studies on neuronal HT-22 cells showed a strong protection against glutamate toxicity for this 15-LOX-1 inhibitor. This provides a novel approach to identify novel small with favorable physicochemical properties for exploring 15-LOX-1 as a drug target in inflammatory diseases and neurodegeneration.

Rational Development of a Potent 15-Lipoxygenase-1 Inhibitor with in Vitro and ex Vivo Anti-inflammatory Properties

Human 15-lipoxygenase-1 (h-15-LOX-1) is a mammalian lipoxygenase and plays an important role in several inflammatory lung diseases such as asthma, COPD, and chronic bronchitis. Novel potent inhibitors of h-15-LOX-1 are required to explore the role of this enzyme further and to enable drug discovery efforts. In this study, we applied an approach in which we screened a fragment collection that is focused on a diverse substitution pattern of nitrogen-containing heterocycles such as indoles, quinolones, pyrazoles, and others. We denoted this approach substitution-oriented fragment screening (SOS) because it focuses on the identification of novel substitution patterns rather than on novel scaffolds. This approach enabled the identification of hits with good potency and clear structure-activity relationships (SAR) for h-1-5-LOX-1 inhibition. Molecular modeling enabled the rationalization of the observed SAR and supported structure-based design for further optimization to obtain inhibitor 14 d that binds with a Ki of 36 nM to the enzyme. In vitro and ex vivo biological evaluations of our best inhibitor demonstrate a significant increase of interleukin-10 (IL-10) gene expression, which indicates its anti-inflammatory properties.

Impact of adiponectin overexpression on allergic airways responses in mice

Obesity is an important risk factor for asthma. Obese individuals have decreased circulating adiponectin, an adipose-derived hormone with anti-inflammatory properties. We hypothesized that transgenic overexpression of adiponectin would attenuate allergic airways inflammation and mucous hyperplasia in mice. To test this hypothesis, we used mice overexpressing adiponectin (Adipo Tg). Adipo Tg mice had marked increases in both serum adiponectin and bronchoalveolar lavage (BAL) fluid adiponectin. Both acute and chronic ovalbumin (OVA) sensitization and challenge protocols were used. In both protocols, OVA-induced increases in total BAL cells were attenuated in Adipo Tg versus WT mice. In the acute protocol, OVA-induced increases in several IL-13 dependent genes were attenuated in Adipo Tg versus WT mice, even though IL-13 per se was not affected. With chronic exposure, though OVA-induced increases in goblet cells numbers per millimeter of basement membrane were greater in Adipo Tg versus WT mice, mRNA abundance of mucous genes in lungs was not different. Also, adiponectin overexpression did not induce M2 polarization in alveolar macrophages. Our results indicate that adiponectin protects against allergen-induced inflammatory cell recruitment to the airspaces, but not development of goblet cell hyperplasia.

Genetic variation in the lipoxygenase pathway and risk of colorectal neoplasia

Arachidonate lipoxygenase (ALOX) enzymes metabolize arachidonic acid to generate potent inflammatory mediators and play an important role in inflammation-associated diseases. We investigated associations between colorectal cancer risk and polymorphisms in ALOX5, FLAP, ALOX12, and ALOX15, and their interactions with nonsteroidal anti-inflammatory drug (NSAID) use. We genotyped fifty tagSNPs, one candidate SNP, and two functional promoter variable nucleotide tandem repeat (VNTR) polymorphisms in three US population-based case-control studies of colon cancer (1,424 cases/1,780 controls), rectal cancer (583 cases/775 controls), and colorectal adenomas (485 cases/578 controls). Individuals with variant genotypes of the ALOX5 VNTR had a decreased risk of rectal cancer, with the strongest association seen for individuals with one or more alleles of >5 repeats (wild type = 5, OR>5/≥5 = 0.42, 95% CI 0.20-0.92; P = 0.01). Four SNPs in FLAP (rs17239025), ALOX12 (rs2073438), and ALOX15 (rs4796535 and rs2619112) were associated with rectal cancer risk at P ≤ 0.05. One SNP in FLAP (rs12429692) was associated with adenoma risk. A false discovery rate (FDR) was applied to account for false positives due to multiple testing; the ALOX15 associations were noteworthy at 25% FDR. Colorectal neoplasia risk appeared to be modified by NSAID use in individuals with variant alleles in FLAP and ALOX15. One noteworthy interaction (25% FDR) was observed for rectal cancer. Genetic variability in ALOXs may affect risk of colorectal neoplasia, particularly for rectal cancer. Additionally, genetic variability in FLAP and ALOX15 may modify the protective effect of NSAID use against colorectal neoplasia.

Induction of apoptosis by Trichostatin A in human breast cancer cell lines: involvement of 15-Lox-1

15-Lipoxygenase-1 (15-Lox-1) is a key enzyme mediating oxidative metabolism of polyunsaturated fatty acids and has attracted considerable interest as a potential target for the induction of apoptosis in cancer cells. Knowledge of relationship between 15-Lox-1 and histone deacetylase inhibitors is lacking in the breast cancer. This study is aimed to investigate the role of Trichostatin A (TSA) and 13(S)-HODE, as a metabolite of 15-Lox-1, in the regulation of breast cancer cell growth. The cytotoxic effect of TSA, as a potent HDAC inhibitor, was measured using MTT assay. Annexin V-FITC and PI staining were performed to detect apoptosis and cell cycle distribution using Flow cytometry. The role of 15-Lox-1 in the regulation of cell growth was assessed by 15-Lox-1 inhibitor and the level of 15-Lox-1 metabolite was measured to determine 15-Lox activity after treatment by TSA. The results demonstrated that TSA induced cell growth inhibition via 15-Lox-1, in a dose- and time-dependent manner, and subsequently accompanied by the cell cycle arrest and induction of apoptosis. Moreover, growth inhibitory effect of TSA was associated with the elevation of 15-Lox-1 metabolite (13(S)-HODE). This study provided evidences that the inhibitory effect of TSA on the breast cancer cell growth occurs via the induction of 15-Lox-1 activity and 13(S)-HODE production. Our findings underline the possible role of 15-Lox-1/13(S)-HODE pathway as a promising molecular approach for the induction of apoptosis in breast cancer cells.

Dendritic cells and alveolar macrophages mediate IL-13-induced airway inflammation and chemokine production

BACKGROUND

IL-13 in the airway induces pathologies that are highly characteristic of asthma, including mucus metaplasia, airway hyperreactivity (AHR), and airway inflammation. As such, it is important to identify the IL-13-responding cell types that mediate each of the above pathologies. For example, IL-13's effects on epithelium contribute to mucus metaplasia and AHR. IL-13's effects on smooth muscle also contribute to AHR. However, it has been difficult to identify the cell types that mediate IL-13-induced airway inflammation.

OBJECTIVE

We sought to determine which cell types mediate IL-13-induced airway inflammation.

METHODS

We treated the airways of mice with IL-13 alone or in combination with IFN-γ. We associated the inhibitory effect of IFN-γ on IL-13-induced airway inflammation and chemokine production with cell types in the lung that coexpress IL-13 and IFN-γ receptors. We then evaluated IL-13-induced responses in CD11c promoter-directed diphtheria toxin receptor-expressing mice that were depleted of both dendritic cells and alveolar macrophages and in CD11b promoter-directed diphtheria toxin receptor-expressing mice that were depleted of dendritic cells.

RESULTS

Dendritic cell and alveolar macrophage depletion protected mice from IL-13-induced airway inflammation and CCL11, CCL24, CCL22, and CCL17 chemokine production. Preferential depletion of dendritic cells protected mice from IL-13-induced airway inflammation and CCL22 and CCL17 chemokine production but not from IL-13-induced CCL11 and CCL24 chemokine production. In either case mice were not protected from IL-13-induced AHR and mucus metaplasia.

CONCLUSIONS

Pulmonary dendritic cells and alveolar macrophages mediate IL-13-induced airway inflammation and chemokine production.